This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. My research focuses on expression, purification and crystallization of an oxidative stress protein CaSSK1 from Candida albicans. Proteins in the histidine-aspartate (His-Asp) Signal transduction system play an important role in the virulence and cell adaptation of Candida albicans (one of the top four causes of nosocomial infectious diseases in human) to oxidative stress. Therefore, these proteins, especially CaSSK1, are promising targets for the development of novel antifungal drugs. And since humans do not have a similar signaling system, drugs developed to inhibit these signal proteins may not have dramatic side effects in human being. The oxidative stress protein CaSSK1 from Candida albicans will be cloned into either E. coli expression plasmids or yeast expression systems. In order to help the protein to fold properly in E. coli expression hosts, appropriate tags will be cloned to the protein. To avoid the protein being degradated by Ubiquitin system inside of the cells, certain yeast expression hosts will be chosen that have certain Ubiquitin genes deleted. The purified protein will be used to obtain protein crystals, so that the structure of CaSSK1 can be solved .